also, it seems Dana has major respect for Nick, don't know why...
I think it's kind of fundamentally silly to proclaim any athlete as bad for any particular sport, outside of cheating/PED issues. Nick Diaz certainly won't make any fans out of those who already dislike MMA, but I really doubt a true "fan" of the sport is going to give up on the whole thing because of one fighters actions, no matter how heinous they might be. A personality flaw in 1/5000 of a population would be pretty poor grounds to pass judgement on anything, and that being said, if someone makes decisions like that do you really want them sitting next to you at an event anyway? The whole " good for the sport/bad for the sport" issue isn't even really the issue people are debating in these situations, it's whether the athlete is perceived as gaining fans for the sport. Sure more fans means more money, but more money isn't necessarily going to further the integrity or refinement of the sport. I mean it probably would. But not necessarily.
And people are currently fighting to get MMA legal in a lot of areas. Those fights are a lot harder when you have people like Nick getting air and TV time, acting the way he does.
You can tell when he speaks that he definitely isn't all there, he must have suffered some severe and permanent head trauma in the past.
I don't know about the head injury thing, since his brother seems like basically a skinnier version of the same person without the publicity. I would totally agree that they've been permanently fucked in some psychologically or emotionally developmental capacity. They remind me a lot of the kids who thought they were MADD tuffz when I was in junior high.
OP has got all valid points. However, I still like Diaz, questionable public behavior and all. Is he bad for MMA? IMO yes but only in a "surfacey" way. Like McCain could use him as a poster child for his position on human cockfighting. For every guy like him in the UFC, you've got another Shane Carwin working civil engineer or Rich Franklin schoolteacher to show the other side.
I couldn't be more different than Nick, yet to me his appeal is the appeal of the underdog - coming up with poverty, a drug culture in a low-income high crime area, and a psych/mental disorder (ADHD) and probably more undiagnosed. I mean it's hard enough to do a press conference without something wrong in your head. Can you imagine what it would be like to try and do that knowing you have some issues and will probably say something f'ed up and everyone will laugh at you and ostracize you? No wonder the dude runs for the hills from press responsibilities.
To me he's real and I realize his reality is a bit f'd up and maybe not like others. But I'm cool with it. I think he's much better for MMA being real than Chael is with recycled Ric Flair lines from pro wrestling.